Reflectorites
Here is a New Scientist article, based on a SCIENCE report, which says
that molecular clocks, the rate of neutral mtDNA mutation, is possibly 100
times faster than previously thought.
If this turns out to be really the case, it would bring any "Mitochondrial
Eve", the last common female genetic ancestor, which has been variously
dated from ~ 400-60 kya, into closer contact with Biblical time-frames.
I have also attached another New Scientist article from the same issue,
which claims that the maximum human life-span might be much longer than the
current estimate of around 120 years.
If this holds up, it could not be ruled out that the ages of the antediluvians
in Genesis 5 (e.g. "Methuselah lived 969 years" -Gn 5:27); were literally
true.
I would imagine that Hugh Ross and the ICR will *love* these!
Whatever happens, this shows that scientific `fact', especially in the field of
human origins, is only as good as the next discovery.
Steve
PS: the links below might not work if you don't have a member's
subscription.
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http://www.newscientist.co.uk/dailynews/news.jsp?id=ns999930
New Scientist magazine
Thu, 28 Sep 2000 00:03:00 GMT
[...]
Running slow
Molecular clocks may be running far faster than thought, with profound
implications for the dating of the origin of humans
The most accurate estimate ever of the speed of the nematode worm's
'molecular clock' suggests it runs 100 times faster than previously thought.
This could have profound implications for forensic science and our
estimates of the age of species, including man, says an American team.
The rate of mutation in mitochondrial DNA is so regular that it forms the
basis of molecular clocks, used to time the progress of evolution. But a
much faster mutation rate would mean the conventionally used 'clock' has
been running slow - at least for the nematode.
Extrapolating the results directly to humans is not possible, say the
scientists. But their results do support recent controversial studies
suggesting that the human molecular clock also runs 100 times faster than
is usually thought.
This may mean that estimates of the divergence between chimpanzees and
humans, and the emergence of modern man, happened much more
recently than currently believed, say the team.
"Our work appears to support human analyses, which have suggested a
very high rate," says Kelley Thomas of the University of Missouri.
"This work is relevant to humans," says Doug Turnbull of the Institute for
Human Genetics at Newcastle University, UK. "If the human mutation
rate is faster than thought, it would have a lot of impact in looking at
human diseases and forensics, as well as the evolutionary rate of humans."
Artificial evolution
Thomas thinks his study provides the most accurate estimate ever of the
mtDNA mutation rate in Caenorhabditis elegans.
Damaging mutations result in the death of a line, meaning they are not
preserved. However to get an accurate estimate of mtDNA mutations, all
mutations must be taken into account. So the team 'artificially evolved' the
worms, allowing them to produce the next generation even if they had
developed debilitating mutations.
The scientists created 200 generations of worms, then compared the
mitochondrial genome of the final generation with the genome of their
original ancestor.
This technique produced a figure of 8.9 mutations for each site for every
million years.
Compare and contrast
Mutation rates of mtDNA in humans are usually estimated by comparing
sequences of DNA from people and other animals. "This is the kind of
analysis that was used to determine that the African origin of modern
humans was about 200,000 years ago," says Thomas.
"The problem with this approach is that you are looking at both the
mutation rate and the effects of natural selection," he says.
The technique would also miss multiple mutations in the same stretch of
mtDNA, says Paul Sharp of the Institute of Genetics at Nottingham
University, UK.
More recent studies have looked at the mtDNA of people who are
distantly related but share a female ancestor. This approach has revealed
higher mtDNA mutation rates. But the results have not been accepted by
many scientists.
Knowing the exact rate of mutation in humans is very important for
forensic science and studies of genetic disease, stresses Turnbull. Forensic
identification often rests on comparing samples of DNA with samples
from suspected relatives. Faster human molecular clocks could complicate
establishing exact relationships, he says.
Source: Science (vol 289, p 2342)
Correspondence about this story should be directed to
latestnews@newscientist.com
1800 GMT, 28 September 2000
(c) Copyright New Scientist, RBI Limited 2000
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http://www.newscientist.co.uk/dailynews/news.jsp?id=ns999931
New Scientist
28 September 2000
[...]
Age old
The maximum human life span is increasing, a fact which may cast doubt
on the idea of a maximum possible age
The maximum human life span is increasing, says an American team. In
fact, the average oldest age at death has been rising for more than a
century and "there is no hint yet that the upward trend is slowing down,"
says John Wilmoth of the University of California, Berkeley.
Wilmoth says he has the first evidence that the maximum age at death is
being pushed back. He thinks his findings throw doubt on some biologists'
claims that the human life span is set at around 120 years.
"Those numbers are out of thin air. Maximum life span is not a biological
constant," he says. "Though whether it can go on indefinitely is difficult to
say."
Dead reckoning
Wilmoth and his colleagues have been studying Swedish death records
held since 1861. Sweden has the world's most complete and accurate
records on birth and death.
In the 1860s, the oldest age at death for Swedish men and women centred
around 101. That average maximum age rose to about 105 in the 1960s
and shot up to 108 in the 1990s.
It is rare for humans to live past 110 years now. "But future generations
could have a higher range," says Wilmoth.
Public health measures are probably to thank for the lengthening in life
span early in the last century, says Wilmoth.
"After 1970, the trend began to slope upward rapidly," he says. "That
corresponds closely with breakthroughs in understanding and treating
heart disease and stroke."
Source: Science (Vol 289, p 2342)
Correspondence about this story should be directed to
latestnews@newscientist.com
1800 GMT, 28 September 2000
Emma Young
[...]
(c) Copyright New Scientist, RBI Limited 2000
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"But that wasn't to say there was no Eve. And while Africa was still the
strongest candidate (in most people's minds), there was the chance-always
subject to sudden and drastic change - that Eve had been where many
people always thought she had been: in the Middle East, land of the Bible
and that chapter called Genesis." (Brown M.H., "The Search for Eve,"
Harper & Row: New York NY, 1990, p.299)
Stephen E. Jones | sejones@iinet.net.au | http://www.iinet.net.au/~sejones
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